Well, in the Productivity Applications section on the Microsoft Office row Under "Notes", it says:
Please note that the bit version of Office which you are running must match the bit version of Cognos for Microsoft Office installed. If you are running 32bit Microsoft Office, you must install the 32bit version of Cognos for Microsoft Office.
I am fairly certain PowerPlay is 32-bit. I do not have have Outlook 64-bit, but I can tell you from experience that a lot of 32-bit software does not play well if at all with 64-bit software. At my workplace, we have 64-bit OS installs but use 32-bit Office for this very reason.